Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 011759

Area Forecast Discussion
National Weather Service Lincoln IL
1159 AM CST Wed Mar 1 2017

Issued at 1045 AM CST Wed Mar 1 2017

Updated forecast today to increase WNW wind speeds a bit higher, to
20-30 mph and gusts of 35 to 45 mph. Also lower temperatures today
as stronger WNW winds/cold air advection brought temperatures down
at bit quicker. Rest of forecast generally looked on track with
just minor adjustments needed. Highs were reached earlier this
morning, with temps gradually slipping into the upper 30s and 40s
during this afternoon behind a cold front.

Late morning surface analysis shows strong 994 mb low pressure
over central lower MI with its cold front extending thru central
IN and western KY/TN. Its convection moved east of IL early this
morning while wrap around light rain/snow showers were over
eastern IA/NW IL and sw WI where cooler temperatures were in the
30s. Temps had already slipped into the upper 30s nw of the IL
river while areas southeast of I-70 had slipped into the lower
50s by 1030 am. Very tight pressure gradient was giving strong WNW
winds of 20-30 mph with gusts of 30-45 mph across CWA this
morning, even with a low overcast stratus deck. Strongest winds
were over NE CWA from Bloomington and Paris northeast and these
areas were approaching wind advisory criteria (sustained 30 mph
for an hour and/or wind gusts of 45 mph or higher).

Latest forecast models deepen surface low pressure from central MI
to 989 mb by sunset into northeast Great Lakes, and to 985 mb by
midnight to north of NY state. As strong low pressure pulls away,
WNW winds will gradually weaken late this afternoon and during this
evening to 15-25 mph. There could be some light rain showers
along and north of I-74 this afternoon while skies stay fairly
cloudy rest of today.


.SHORT TERM...(Today and tonight)
ISSUED AT 300 AM CST Wed Mar 1 2017

Residual showers and isolated thunderstorms will continue this
morning for Central Illinois... with the better chances for thunder
in the southeastern portions of Illinois. Colder temperatures in
general expected for today and tonight. Although high temperatures
today are expected in the upper 40s and lower 50s...the blustery
winds out of the NW to 20-25 mph will make it feel more like the 30s.
Skies expected to slowly clear from the SW later this afternoon.
Drier air moving in competing with low level RH enhanced by storms,
humidity will approach 90 percent in some areas towards dawn
Thursday morning, but the winds expected to stay up enough to
prevent widespread fog issues.

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 300 AM CST Wed Mar 1 2017

Models continue with forecasting a couple of clipper systems moving
through a portion of the CWA the last two days of this week. Good
agreement is seen with the first one, Thur afternoon and Thur
evening. This clipper will move across northeastern third of the
state so the chance pops will mainly along and northeast of I-74.
The second system will be Friday night and the models differ some
with the timing and the amount of precip expected. Since both
clippers move through the area during the night time hours, temps
are expected to be below freezing. So, precip will be rain showers
or snow as temps drop during the evening and overnight hours. Brief
periods of dry weather are expected in between the systems as well
as through the weekend after the second clipper.

The next chance of significant precip will be the beginning of next
week, Sunday night through Monday night. Models differ considerably
with timing and extent of precip through this period, with the GFS
slower, the Canadian fastest, and the ECMWF in-between. So will keep
with a model blend for this time period and let the models work
themselves out over the next several days. Temps will also be warm
from the weekend into the beginning of next week, so all precip will
be rain during this time period.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1159 AM CST Wed Mar 1 2017

Strong WNW winds of 20-25 kts and gusts of 30-35 kts this
afternoon will gradually dimininsh late this afternoon and
evening. Winds will diminish to 7-11 kts during mid or late
evening and continue near that speed through Thu morning.
Strong 991 mb low pressure over southeast Ontario will deepen to
985 mb just north of NY state by midnight tonight and to 983 mb
over northern Maine by sunrise Thu. Very tight pressure gradient
over central IL this afternoon will weaken this evening allowing
WNW winds to diminish. MVFR stratus clouds 1-3k ft over central IL
early this afternoon will gradually lift to VFR later this
afternoon and early evening, then scatter out overnight, lasting
longest at BMI and CMI. Isolated light rain showers this afternoon
over central IL, especially near I-74 and carried VCSH for this.
Brunt of light precipitation to pass north/ne of central IL
airports this afternoon.




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